Currently, large-size glass substrate film sputtering targets used in the thin film transistor liquid crystal display (TFT-LCD) industry are produced in a process mainly comprising the following steps: weighing→mixing granulation→forming→drying→sintering→processing. Among these steps, the forming step and the sintering step have the most prominent influence on subsequent use of the sputtering targets in panel producing factories. The primary processes currently adopted for forming and sintering include hot pressing and cool pressing. However, both hot pressing and cool pressing have the following shortcomings.
Firstly, targets prepared through these two processes all present an insufficient relative density and entrainment of gases such as oxygen inside the crystal grains and at the grain boundaries. Micro-cavities present on the target surface make distribution of the electric field on the target surface uneven, which makes it very likely to cause a strong electric field on the surface. Additionally, argon (Ar) atoms impacting the target in local regions have very high energy and can dissociate the oxygen atoms to form high resistance regions; consequently, the resulting film tends to accumulate and bulge gradually to cause poor uniformity of the resulting film and large roughness of the film surface.
Secondly, the sintering time is too long and the sintering process mainly relies on heat conduction and heat radiation of the heating element, which makes the grain size of the target too large. Consequently, the “structure inheritance effect” caused during the physical vapor deposition (PVD) process in the panel producing factory makes the grain size of the deposited film relatively large and non-uniform, which is unfavorable for development of large-size panels.
Thirdly, the finer the particle size of the sintered powder is, the more the foreign elements adsorbed will be. Therefore, aggregated foreign ions or adsorbed gas molecules will arise at the grain boundaries due to diffusion in the long-time sintering process. Similarly, pollutions that will degrade the product yield and the product quality also arise in the process of forming the film through physical vapor deposition in the panel producing factory.
Accordingly, an urgent need exists in the art to provide a preparing method of a glass substrate film sputtering target that can solve the aforesaid problems.